Create custom layouts for Wear

With Wear OS by Google, creating layouts for a watch is similar to creating
them for a phone, except that you have to design for the screen size and for
glanceability. Do not port the functionality and UI from a phone app to a
watch and expect a good experience.

You should create custom layouts only when necessary. Read the
Designing for Wear OS
guidelines for information on designing great watch apps.

Create custom notifications

In general, you should create notifications on the phone and let them
automatically sync to the wearable. This lets you build your
notifications once and have them appear on many types of devices (not
just watches, but eventually Auto and TV) without having to design them
for different form factors.

If the standard notification styles don't work for you (such as
NotificationCompat.BigTextStyle or
NotificationCompat.InboxStyle), you can display
an activity with a custom layout. You can only create and issue custom
notifications on the watch, and the system does not sync these
notifications to the phone.

Note:
When creating custom notifications on the watch, you can use
the standard notification APIs (API Level 20) instead of the Support
Library.

To create a custom notification:

Create a layout and set it as the content view for the activity that
you want to display.

Define necessary properties for the activity in the Android manifest
to allow the activity to be displayed in the watch's context stream
process. You need to declare the activity to be exportable, be
embeddable, and have an empty task affinity. We also recommend setting
the theme to Theme.DeviceDefault.Light. For example:

Note:
In Wear 1.x, when a notification is peeking on the homescreen, the
system displays it with a standard template that it generates from
the notification's semantic data. This template works well on all
watchfaces. When users swipe the notification up, they'll then see
the custom activity for the notification.

Create layouts with the Wear UI Library

The Wear UI Library is automatically included when you create your
watch app with the Android Studio Project Wizard. You can also add this
library to your build.gradle file with the following
dependency declaration: